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2 Federal Aviation Administration E-Tablet Fire Tests Background There is use of E-Tablets as an airline supplied personal entertainment device aboard passenger aircraft. Lithium-ion batteries are known to undergo “thermal runaway” and propagate “thermal runaway” to additional adjacent batteries. Large quantities of e-tablets stored adjacent to each other can lead to a significant fire.

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4 Federal Aviation Administration E-Tablet Fire Tests Objective Perform experiments to understand the fire hazard of storage of large quantities of e-tablets. –Variation of e-tablet spacing. 1 inch separation No separation –Variation of e-tablet orientation. Horizontal orientation vs. vertical orientation. –Variation of e-tablet battery capacity. Battery storage capacity varies among e-tablets and is known to contribute to the heat of reaction. –Variation of the manufacturer of the e-tablet. E-tablet materials vary among manufacturers and may contribute differently to the fire hazard (e.g. aluminum vs. plastic). –Variation of ignition source. Alcohol fire: Simulated an external fire leading to thermal runaway in battery Heat plate: Simulated an adjacent battery in thermal runaway –Determine the hazard of the accumulation of unburnt battery hydrocarbons.

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5 Federal Aviation Administration E-Tablet Fire Tests Test Setup Three types of e-tablets were used: –Type 1: 43 Wh capacity, aluminum case material. –Type 2: 25 Wh capacity, aluminum case material. –Type 3: 25.9 Wh capacity, plastic case material. Heat from a hot plate or alcohol fire was used to initiate thermal runaway. Temperature data was collected. –Thermocouples were positioned on the front and back of each tablet. –A thermocouple was placed on the top of the cart. –A thermocouple was positioned to determine ambient air temperature within the cart. –Finally, temperature on the outside of the cart was measured with an IR camera. A pressure transducer was attached to measure pressure within the cart. Later tests were done in a 737 passenger aircraft with a 20 kJ spark igniter placed in the bottom of the cart. –The aircraft had supplied air ventilation from an external ground cart.

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11 Federal Aviation Administration E-Tablet Fire Tests Results: Tests in 737 (con’t) Combustion occurred within the galley cart. –Combustion before the hydrocarbons had completely spread throughout the inside of the cart caused localized flaming which penetrated the door seal. –Combustion after the hydrocarbons had completely spread throughout the inside of the cart caused a pressure pulse that caused the cart door to burst open. Despite use of the aircraft ventilation system, the aircraft filled with smoke. 11

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13 Federal Aviation Administration E-Tablet Fire Tests Summary of Results Higher battery capacities produced higher e-tablet temperatures. E-tablets made of aluminum were able to absorb more heat than plastic e-tablets before reaching thermal runaway. The build-up of hydrocarbons within the cart produced a flammable mixture, which when ignited caused the door to burst open and release flames and smoke in large enough quantities to overpower the aircraft ventilation system. 13